<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>dd</title>
    <script src="../../scripts/jquery/2.0.3/jquery-2.0.3.js"></script>
    <script>
        $(function () {
            $(".aa").click(function () {
                $("body").append('<div class="cc" style="height:30px;background: black;margin: 10px;"></div>');
            })
            $(".bb").click(function () {
                $(".cc").remove();
            })
        });
    </script>
</head>
<body>
<div class="aa" style="height: 30px;background: black;margin: 10px;">增加</div>
<div class="bb" style="height: 30px;background: black;margin: 10px;">减少</div>
<div class="aa" style="height: 30px;background: black;margin: 10px;"></div>
</body>
</html>